Thermal monitoring of a Cryosol in a high marine terrace (Half Moon Island, Maritime Antarctica).

Active layer and permafrost are important indicators of climate changes in periglacial areas of Antarctica, and the soil thermal regime of Maritime Antarctica is sensitive to the current warming trend. This research aimed to characterize the active layer thermal regime of a patterned ground located at an upper marine terrace in Half Moon Island, during 2015-2018. Temperature and moisture sensors were installed at different soil depths, combined with air temperature, collecting hourly data. Statistical analysis was applied to describe the soil thermal regime and estimate active layer thickness. The thermal regime of the studied soil was typical of periglacial environment, with high variability in temperature and water content in the summer, resulting in frequent freeze-thaw cycles. We detected dominant freezing conditions, whereas soil temperatures increased, and the period of high soil moisture content lasted longer over the years. Active layer thickness varied between the years, reaching a maximum depth in 2018. Permafrost degradation affects soil drainage and triggers erosion in the upper marine terrace, where permafrost occurrence is unlikely. Longer monitoring periods are necessary for a detailed understanding on how current climatic and geomorphic conditions affect the unstable permafrost of low-lying areas of Antarctica (marine terraces).

Soils under seal carcasses with varying degrees of decomposition: oasis of nutrients and vegetation in Antarctica.

Areas of high concentration of seal carcasses have been observed in localized areas of James Ross Island, Antarctica. Such carcasses show an unusual vegetation development, in a semi-arid area with bare soils under intense winds, high salinity and sandy texture. We investigated carcasses of seals around a lake in James Ross Island, with four different stages of decomposition, with three replicates: Seal (S01), with recently mummified carcasses; S02, with partially degraded carcasses; S03, with broken carcasses with partially degraded exposed bones, and S04, with completely broken, scattered skeletons. The vegetation showed a maximum degree of development in carcasses at stages S02 and S03, with the environment between the skin and the skeleton as the preferred place for vegetation establishment. The chemical alteration was greater with increasing carcass decomposition but reduced with the spreading and final decomposition of the bones, with anomalous values observed only in the vicinity of the carcasses. It is concluded that the presence of carcasses of seals, concentrated in wet places, even in a semi-desert climate, represent important oases of nutrients, with a combination of physical and chemical effects throughout the decomposition process that favor plant establishment and succession.

Pellets of Stercorarius spp. (skua) as plant dispersers in the Antarctic Peninsula.

The Antarctic Peninsula has experienced some of the most accelerated warming worldwide, resulting in the retreat of glaciers and creation of new areas for plant development. Information regarding the plant dispersal processes to these new niches is scarce in Antarctica, despite birds being important vectors elsewhere. Many bird pellets (with feed remains such as bones and feathers) are generated annually in Antarctica, which are light and easily transported by the wind and include vegetation that is accidentally or purposely swallowed. The aim of this study was to analyze the presence of plant fragments within skua (Stercorarius/Catharacta spp.) pellets collected from two sampling areas in the Maritime Antarctic: Stinker Point (Elephant Island, 17 samples) and Byers Peninsula (Livingston Island, 60 samples), in the South Shetland Archipelago, during the austral summers of 2018 and 2020. In both study areas, five species of Bryophyta were found that were associated with the pellets and viable in germination tests in a humid chamber. The ingestion of Bryophyta for the skuas contribute to the dispersion of different moss species, including to areas recently exposed by the ice retreat. This is the first demonstration that skua pellets effectively act in the dispersion of Antarctic mosses.

Soil-landform-vegetation interplays at Stinker Point, Elephant Island, Antarctica.

The geomorphic dynamics on ice-free areas are crucial for understanding soil formation, vegetation and landscape stability in maritime Antarctic. We aimed to describe the soil formation on different landforms, following the Holocene glacial retreat at Stinker Point. Twenty profiles were sampled and classified, grouped into three landforms units: middle platforms and scarps, till/glacial deposits and present/Holocene raised beaches. Soil chemical and physical attributes were determined, and the vegetation type identified and quantified. Soils from till and glacial deposits can be separated by the age of exposure: older soils are stony, skeletic; and recently exposed till has soils with moderate depth, alkaline reaction and very high base saturation. Soils at the middle platforms are shallow, coarse-grained, skeletic, with abundant vegetation. Soils from the present-day beaches are alkaline, very coarse with no horizon differentiation, whereas soils on Holocene beaches are acid and nutrient-rich due to past or present-day influence of fauna. Soils from Stinker Point are generally shallow, skeletic and strongly related to the landforms and biogenic influences. Compared with other islands of the South Shetlands, in Elephant Island soil development is less pronounced, being this mainly attributed to the metamorphic nature of parent material, with greater resistance to weathering.

Changes in plant communities and soil attributes in the "Cousteau's whale bone skeleton" tourist attraction area in Keller Peninsula after 48 years.

Ice-free areas of Antarctica represent an important study region that helps us understand how human activity affects plant communities and soil properties. The goal of this study was to determine the changes in plant composition and soil properties around a whale bone skeleton (WB) near Ferraz Station, King George Island, Antarctica from 1972 to 2020 (48 years). The WB was assembled in 1972 by Jacques-Yves Cousteau and his team. It is located in a large moss field and visited by many tourists. We studied the plant composition and development based on historical and recent photographs and phytosociological studies from 1986 to 2020. The soil was sampled in February 2009 to determine general properties. The results showed that human activity surrounding the WB directly affected the plant community composition and soil properties. The Syntrichia cushions were positively affected by the calcium deposits from bone dissolution. The principal component analysis revealed that mineralization of the bones increased soil nutrient assembly. A strong phosphatization process was observed in the WB area, similar to that in ornithogenic soils. The WB on the marine terrace enhanced soil fertility and changed the plant community.

Species composition, diversity and coverage pattern of associated communities of mosses-lichens along a pedoenvironmental gradient in Maritime Antarctica.

Maritime Antarctica is one of the major terrestrial ecosystems dominated by lichens and mosses, which represent important ecological indicators. Thus, we aimed to evaluate the changes in associated communities of mosses-lichens diversity and coverage along a pedoenvironmental gradient on Half Moon Island, Maritime Antarctica. We focused on how patterns in associated communities of mosses-lichens species diversity (richness, species composition and beta diversity) and coverage are associated with soil properties using plant inventory data from 174 plots across 14 contrasting pedoenvironments. The results clearly show marked differences in soil properties along the pedoenvironmental gradient, which determine variations in species composition, richness and coverage. We presumed that these variations are common in Maritime Antarctica owing to varying periglacial processes, weathering degree, parent material and biological influence (especially by penguins and other birds). The community species richness and coverage along the pedoenvironmental gradient differ, nevertheless share common species present in most pedoenvironments, despite differences in coverage. We assume that most of the pedoenvironments are habitats to rare species that occur only under specific soil conditions, additionally promotes high ß-diversity between pedoenvironments and low species similarity.

Interplay Between J- and H-Type Coupling in Aggregates of π-Conjugated Polymers: A Single-Molecule Perspective.

Strong dipole-dipole coupling within and between π-conjugated segments shifts electronic transitions, and modifies vibronic coupling and excited-state lifetimes. Since J-type coupling between monomers along the conjugated-polymer (CP) chain and H-type coupling of chromophores between chains of a CP compete, a superposition of the spectral modifications arising from each type of coupling emerges, making the two couplings hard to discern in the ensemble. We introduce a single-molecule H-type aggregate of fixed spacing and variable length of up to 10 nm. HJ-type aggregate formation is visualized intuitively in the scatter of single-molecule spectra.

CYP106A2-A versatile biocatalyst with high potential for biotechnological production of selectively hydroxylated steroid and terpenoid compounds.

CYP106A2 from Bacillus megaterium ATCC13368, was identified in the 1970s as one of the first bacterial steroid hydroxylases responsible for the conversion of progesterone to 15ß-hydroxyprogesterone. Later on it has been proven to be a potent hydroxylase of numerous 3-oxo-Δ4 as well as 3-hydroxy-Δ5-steroids and has recently also been characterized as a regioselective allylic bacterial diterpene hydroxylase. The main hydroxylation position of CYP106A2 is thought to be influenced by the functional groups at C3 position in the steroid core leading to a favored 15ß-hydroxylation of 3-oxo-Δ4-steroids and 7ß-hydroxylation of 3-hydroxy-Δ5-steroids. However, in some cases the hydroxylation is not strictly selective, resulting in the formation of undesired side-products. To overcome the unspecific hydroxylations or, on the contrary, to gain more of these products in case they are of industrial interest, rational protein design and directed evolution have been successfully performed to shift the stereoselectivity of hydroxylation by CYP106A2. The subsequently obtained hydroxylated steroid and terpene derivatives are especially useful as drug metabolites and drug precursors for the pharmaceutical industry, due to their diverse biological properties and hardship of their chemical synthesis. As a soluble prokaryotic P450 with broad substrate spectrum and hydroxylating capacity, CYP106A2 is an outstanding candidate to establish bioconversion processes. It has been expressed with respectable yields in Escherichia coli and Bacillus megaterium and was applied for the preparative hydroxylation of several steroids and terpenes. Recently, the application of the enzyme was assessed under process conditions as well, depicting a successfully optimized process development and getting us closer to industrial scale process requirements and a future large scale application. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone.

Comparison of CYP106A1 and CYP106A2 from Bacillus megaterium - identification of a novel 11-oxidase activity.

The CYP106A subfamily hydroxylates steroids, diterpenes, and triterpenes in a regioselective and stereoselective manner, which is a challenging task for synthetic chemistry. The well-studied CYP106A2 enzyme, from the Bacillus megaterium strain ATCC 13368, is a highly promising candidate for the pharmaceutical industry. It shares 63 % amino acid sequence identity with CYP106A1 from B. megaterium DSM319, which was recently characterized. A focused steroid library was screened with both CYP106A1 and CYP106A2. Out of the 23 tested steroids, 19 were successfully converted by both enzymes during in vitro and in vivo reactions. Thirteen new substrates were identified for CYP106A1, while the substrate spectrum of CYP106A2 was extended by seven new members. Finally, six chosen steroids were further studied on a preparative scale employing a recombinant B. megaterium MS941 whole-cell system, yielding sufficient amounts of product for structure characterization by nuclear magnetic resonance. The hydroxylase activity was confirmed at positons 6ß, 7ß, 9α, and 15ß. In addition, the CYP106A subfamily showed unprecedented 11-oxidase activity, converting 11ß-hydroxysteroids to their 11-keto derivatives. This novel reaction and the diverse hydroxylation positions on pharmaceutically relevant compounds underline the role of the CYP106A subfamily in drug development and production.

Steroid conversion with CYP106A2 - production of pharmaceutically interesting DHEA metabolites.

BACKGROUND: Steroids are lipophilic compounds with a gonane skeleton and play an important role in higher organisms. Due to different functionalizations - mainly hydroxylations - at the steroid molecule, they vary highly in their mode of action. The pharmaceutical industry is, therefore, interested in hydroxysteroids as therapeutic agents. The insertion of hydroxyl groups into a steroid core, however, is hardly accomplishable by classical chemical means; that is because microbial steroid hydroxylations are investigated and applied since decades. CYP106A2 is a cytochrome P450 monooxygenase from Bacillus megaterium ATCC 13368, which was first described in the late 1970s and which is capable to hydroxylate a variety of 3-oxo-delta4 steroids at position 15beta. CYP106A2 is a soluble protein, easy to express and to purify in high amounts, which makes this enzyme an interesting target for biotechnological purposes. RESULTS: In this work a focused steroid library was screened in vitro for new CYP106A2 substrates using a reconstituted enzyme assay. Five new substrates were identified, including dehydroepiandrosterone and pregnenolone. NMR-spectroscopy revealed that both steroids are mainly hydroxylated at position 7beta. In order to establish a biotechnological system for the preparative scale production of 7beta-hydroxylated dehydroepiandrosterone, whole-cell conversions with growing and resting cells of B. megaterium ATCC1336 the native host of CYP1062 and also with resting cells of a recombinant B. megaterium MS941 strain overexpressing CYP106A2 have been conducted and conversion rates of 400 muM/h (115 mg/l/h) were obtained. Using the B. megaterium MS941 overexpression strain, the selectivity of the reaction was improved from 0.7 to 0.9 for 7beta-OH-DHEA. CONCLUSIONS: In this work we describe CYP106A2 for the first time as a regio-selective hydroxylase for 3-hydroxy-delta5 steroids. DHEA was shown to be converted to 7beta-OH-DHEA which is a highly interesting human metabolite, supposed to act as neuroprotective, anti-inflammatory and immune-modulatory agent. Optimization of the whole-cell system using different B. megaterium strains lead to a conversion of DHEA with B. megaterium showing high selectivity and conversion rates and displaying a volumetric yield of 103 mg/l/h 7beta-OH-DHEA.

Chatbot-Mediated Learning For Caregiving Relatives of People With Dementia: Empirical Findings and Didactical Implications For Mulitprofessional Health Care.

Purpose: Supporting family caregivers is a major challenge for the healthcare system. The first points of contact are physicians, nurses and social services, which are not easily accessible. For this reason, an information platform has been developed to provide information for family caregivers caring for people with dementia at home. The aim of this article is to provide an insight into the didactic design of this platform. Sample and Methods: A didactic concept was developed based on didactic target group analysis and interviews with caring relatives (n=6). Results: The didactic concept of the digital platform takes into account the characteristics of family caregivers as learners, such as time constraints and reciprocity. Therefore two different learning paths, a long and a short version, are offered. Reciprocity is supported by information which are related to individual characteristics of the caring relation. This is made possible by an adaptation of the didactic method "anchored instructions": Family caregivers experience a problematic caring situation. They use the platform and central concepts related to this situation are offered as anchors. In chatbot mediated learning, these concepts are identified and, ideally, relevant information is provided in a short version. These concepts are displayed as a learning map and must be proactively selected. Chatbot mediated learning has the advantage that matching concepts are offered as a pre-selection. Especially for inexperienced carers who are not familiar with the concepts, this learning path seems to be suitable. Conclusion: The combination of learning through the "Information for Relatives" website and CML seems to meet all needs. In order to promote learner motivation, the chatbot should not only offer the identified concept, but also those related to this concept, in order to link new knowledge in one's own knowledge network.

Temporal switching of homo-FRET pathways in single-chromophore dimer models of π-conjugated polymers.

A set of π-conjugated oligomer dimers templated in molecular scaffolds is presented as a model system for studying the interactions between chromophores in conjugated polymers (CPs). Single-molecule spectroscopy was used to reveal energy transfer dynamics between two oligomers in either a parallel or oblique-angle geometry. In particular, the conformation of single molecules embedded in a host matrix was investigated via polarized excitation and emission fluorescence microscopy in combination with fluorescence correlation spectroscopy. While the intramolecular interchromophore conformation was found to have no impact on the fluorescence quantum yield, lifetime, or photon statistics (antibunching), the long-term nonequilibrium dynamics of energy transfer within these bichromophoric systems was accessible by studying the linear dichroism in emission at the single-molecule level, which revealed reversible switching of the emission between the two oligomers. In bulk polymer films, interchromophore coupling promotes the migration of excitation energy to quenching sites. Realizing the presence and dynamics of such interactions is crucial for understanding limitations on the quantum efficiency of larger CP materials.

Awareness and knowledge of diabetic ketoacidosis in people with type 1 diabetes: a cross-sectional, multicenter survey.

INTRODUCTION: To evaluate awareness and knowledge of diabetic ketoacidosis (DKA), a common and potentially life-threatening complication in people living with type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS: A survey was developed to assess individuals' current knowledge, management, and unmet needs regarding DKA. The study was conducted in six Swiss and three German endocrine outpatient clinics specialized in the treatment of diabetes. RESULTS: A total of 333 participants completed the questionnaire (45.7% female, mean age of 47 years, average duration of T1D at 22 years). Surprisingly, 32% of individuals were not familiar with the term 'diabetic ketoacidosis'. Participants rated their own knowledge of DKA significantly lower than their physicians (p<0.0001). 46% of participants were unable to name a symptom of DKA, and 45% were unaware of its potential causes. 64% of participants did not test for ketones at all. A significant majority (67%) of individuals expressed the need for more information about DKA. CONCLUSIONS: In patients treated in specialized centers, knowledge of DKA was found to be inadequate, with a lack of understanding regarding symptoms and causes. Healthcare professionals tended to overestimate individuals' knowledge. Future efforts should focus on addressing these knowledge gaps and incorporating protective factors into the treatment of T1D.

Shape-persistent linear, kinked, and cyclic oligo(phenylene-ethynylene-butadiynylene)s: self-assembled monolayers.

Shape-persistent rigid phenylene-ethynylene-butadiynylenes form lamellar self-assembled monolayers (SAMs) at the HOPG/TCB interface, which were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers.

H-Aggregation Effects between π-Conjugated Chromophores in Cofacial Dimers and Trimers: Comparison of Theory and Single-Molecule Experiment.

Excited-state interchromophoric couplings in π-conjugated polymers present a daunting challenge to study as their spectroscopic signatures are difficult to separate from structure-dependent intrachromophoric spectral characteristics. Using custom-designed molecular model systems in combination with single-molecule spectroscopy, a controlled coupling of the excited states between cofacially arranged π-conjugated oligomers is shown to be possible. Multiscale molecular dynamics simulations allow us to generate a representative ensemble of molecular structures of the model molecule embedded in a polymer matrix and examine the connection between structural fluctuations of the molecule with theoretically predicted and measured spectral signatures. The single molecules in the embedding matrix polymer can be assigned to specific conformational features with the help of computer-based "virtual spectroscopy". By combining a quantum chemical approach with an analytical approach, we show that the coupling between the chromophores is well-described by transition dipole coupling above an interchromophoric separation of ∼4.5 Å. Even for aligned chromophores, however, twisting between repeat units of the π-system and bending of the individual π-systems can lead to a decoupling of the chromophores to a degree far beyond what their equilibrium structures would suggest: tiny displacements of the molecular constituents can dramatically impact excited-state interactions. This observation has profound implications for the design of future tunable organic optoelectronic materials.

Long-term plasticity of visually evoked potentials in humans is altered in major depression.

BACKGROUND: Long-term synaptic plasticity is a ubiquitous form of neuronal plasticity that regulates the strength of synaptic transmission in many brain areas. However, most data on long-term potentiation and long-term depression rely on research in animal brain slices. The role of synaptic plasticity in physiology and pathology of the functioning human brain remains obscure. Considering recent studies that provided evidence for a dysfunction of brain plasticity as the neurobiological basis of affective disorders, we assessed neural transmission and its plastic modulation in the visual pathway in healthy control subjects and patients with major depression. METHODS: Recordings of visually evoked potentials (VEPs) in humans. RESULTS: Prolonged visual presentation of checkerboard reversals resulted in a sustained amplitude modulation of early components of subsequent VEPs. After a 10-min block of visual stimulation (two checkerboard reversals per second), the C1 component was reduced, whereas P1 and N1 were both significantly increased for >30 min. Chronic application of the selective serotonin reuptake inhibitor sertraline in healthy control subjects augmented these effects, whereas the polarity of the modulation was inverted in patients with severe major depression. Moreover, early VEP amplitudes were decreased in depressed patients when compared with matched control subjects and increased in normal control subjects after chronic intake of an antidepressant. CONCLUSIONS: Our results demonstrate that stimulus-induced response plasticity of VEPs can be induced in the human brain and is sharing properties with hebbian forms of synaptic plasticity. Major depression and antidepressant treatment of healthy control subjects differentially modulate amplitude and plasticity of evoked potentials. This study provides direct evidence in humans for a central role of synaptic plasticity in the pathophysiology of depression.

Biotransformation of prednisone and dexamethasone by cytochrome P450 based systems - Identification of new potential drug candidates.

Prednisone and dexamethasone are synthetic glucocorticoids widely used as anti-inflammatory and immunosuppressive drugs. Since their hydroxylated derivatives could serve as novel potential drug candidates, our aim was to investigate their biotransformation by the steroid hydroxylase CYP106A2 from Bacillus megaterium ATCC13368. In vitro we were able to demonstrate highly selective 15ß-hydroxylation of the steroids with a reconstituted CYP106A2 system. The reactions were thoroughly characterized, determining the kinetic parameters and the equilibrium dissociation constant. The observed lower conversion rate in the case of dexamethasone hydroxylation was clarified by quantum chemical calculations, which suggest a rearrangement of the intermediately formed radical species. To identify the obtained conversion products with NMR, CYP106A2-based Bacillus megaterium whole-cell systems were applied resulting in an altered product pattern for prednisone, yet no significant change for dexamethasone conversion compared to in vitro. Even the MS941 control strain performed a highly selective biotransformation of prednisone producing the known metabolite 20ß-dihydrocortisone. The identified novel prednisone derivatives 15ß, 17, 20ß, 21-tetrahydroxy-preg-4-en-3,11-dione and 15ß, 17, 20ß, 21-tetrahydroxy-preg-1,4-dien-3,11-dione as well as the 15ß-hydroxylated variants of both drugs are promising candidates for drug-design and development approaches.

Properties, promotive and obstructive conditions of multi-professional teaching and learning of health professions and non-health professions: an explorative survey from the perspective of teachers.

OBJECTIVE: Care for people with dementia is considered a multi-professional challenge that requires a collaborative approach between health professionals and non-health professionals. Didactic strategies to ensure the same qualifications across these occupational groups are lacking. This article presents the joint learning of selected properties and promotive and obstructive conditions, using the example of a multi-professional Master's programme. It subsequently draws conclusions for didactic concepts. METHODOLOGY: The perceptions of 12 teachers on this Master's programme, all representing different professions, were determined by using a qualitative exploratory survey on the three stated dimensions. With the aid of a summarising content analysis, their statements were condensed and abstracted so as to deduce appropriate requirements for methodical and didactic learning scenarios. RESULTS: In view of the fact that the students have very varied previous knowledge, the main challenge is finding a balance between expertise and tediousness. Establishing essential and common expertise, as well as sensitivity for different perspectives, is made particularly difficult by the fact that health and non-health professions differ greatly in terms of methods and approaches. For a successful outcome, the content focal points and didactic and methodical concepts for a learning group need to take into account the composition of that specific group. Recourse to didactic standard concepts is only possible to a limited extent. CONCLUSIONS: The aim of joint teaching and learning of health and non-health professionals is to enhance the understanding of a profession: This is done by making individuals aware of their role in the chain of care, so they can recognise and organise the mutual conditionality of their own and external professional contributions.

Toward establishing a morphological and ultrastructural characterization of proembryogenic masses and early somatic embryos of Araucaria angustifolia (Bert.) O. Kuntze.

Somatic embryogenesis is a morphogenetic route useful for the study of embryonic development, as well as the large-scale propagation of endangered species, such as the Brazilian pine (Araucaria angustifolia). In the present study, we investigated the morphological and ultrastructural organization of A. angustifolia somatic embryo development by means of optical and electron microscopy. The proembryogenic stage was characterized by the proliferation of proembryogenic masses (PEMs), which are cellular aggregates composed of embryogenic cells (ECs) attached to suspensor-like cells (SCs). PEMs proliferate through three developmental stages, PEM I, II, and III, by changes in the number of ECs and SCs. PEM III-to-early somatic embryo (SE) transition was characterized by compact clusters of ECs growing out of PEM III, albeit still connected to it by SCs. Early SEs showed a dense globular embryonic mass (EM) and suspensor region (SR) connected by embryonic tube cells (TCs). By comparison, early somatic and zygotic embryos showed similar morphology. ECs are round with a large nucleus, nucleoli, and many cytoplasmic organelles. In contrast, TCs and SCs are elongated and vacuolated with cellular dismantling which is associated with programmed cell death of SCs. Abundant starch grains were observed in the TCs and SCs, while proteins were more abundant in the ECs. Based on the results of this study, a fate map of SE development in A. angustifolia is, for the first time, proposed. Additionally, this study shows the cell biology of SE development of this primitive gymnosperm which may be useful in evolutionary studies in this area.